The present invention relates to an autofocusing system in the macro zone of a zoom lens.
With the progress of electronic technology, there have recently been developed varieties of automatic focusing camera equipped with power zoom lenses whose zooming lens group is driven by a drive means, such as a motor.
Some autofocusing systems of the sort mentioned above have a so-called "focus-lock function", in which if a photometric switch is actuated after an in-focus state is established by means of the autofocusing system, the operation of the autofocusing system can be suspended until the suspension of the operation is released, for the purpose of allowing a photographer to determine a composition in the finder.
With a zoom lens mounted on a camera equipped with an autofocusing system having such a focus-lock function, however, it is generally desired that zooming be executed even in the aforementioned focus-lock state.
On the other hand, the zooming lens group is designed to form an image of an object on a film at all times if it is in a zooming zone. Nevertheless, the zooming operation, when performed, may cause a deviation, depending on the zooming lens group, from the proper image-forming position for reasons of e.g., the process of manufacturing of the lens.
For the reason set forth above, the in-focus state is not always maintainable when the zoom lens in the in-focus state brought about by the autofocusing system, is moved. If a picture is taken in that condition, blurring of the image may occur.